as.data.frame              package:base              R Documentation

_C_o_e_r_c_e _t_o _a _D_a_t_a _F_r_a_m_e

_D_e_s_c_r_i_p_t_i_o_n:

     Functions to check if an object is a data frame, or coerce it if
     possible.

_U_s_a_g_e:

     as.data.frame(x, row.names = NULL, optional = FALSE)
     is.data.frame(x)

_A_r_g_u_m_e_n_t_s:

       x: any R object.

row.names: 'NULL' or a character vector giving the row names for the
          data frame.  Missing values are not allowed.

optional: logical. If 'TRUE', setting row names and converting column
          names (to syntactic names) is optional.

_D_e_t_a_i_l_s:

     'as.data.frame' is a generic function with many methods, and users
     and packages can supply further methods.

     If a list is supplied, each element is converted to a column in
     the data frame.  Similarly, each column of a matrix is converted
     separately. This can be overridden if the object has a class which
     has a method for 'as.data.frame': two examples are matrices of
     class '"model.matrix"' (which are included as a single column) and
     list objects of class '"POSIXlt"' which are coerced to class
     '"POSIXct"'

     Character variables are converted to factor columns unless
     protected by 'I'.

     If a data frame is supplied, all classes preceding '"data.frame"'
     are stripped, and the row names are changed if that argument is
     supplied.

     If 'row.names = NULL', row names are constructed from the names or
     dimnames of 'x', otherwise are the integer sequence starting at
     one.  Few of the methods check for duplicated row names.

_V_a_l_u_e:

     'as.data.frame' returns a data frame, normally with all row names
     '""' if 'optional = TRUE'.

     'is.data.frame' returns 'TRUE' if its argument is a data frame
     (that is, has '"data.frame"' amongst its classes) and 'FALSE'
     otherwise.

_N_o_t_e:

     In versions of R prior to 1.4.0 logical columns were converted to
     factors (as in S3 but not S4).

_R_e_f_e_r_e_n_c_e_s:

     Chambers, J. M. (1992) _Data for models._ Chapter 3 of
     _Statistical Models in S_ eds J. M. Chambers and T. J. Hastie,
     Wadsworth & Brooks/Cole.

_S_e_e _A_l_s_o:

     'data.frame'

